Welcome to Trouble Free Pool

We would like to welcome you to TFP, the webs leading Pool related website. We invite you to please Register to create a new account. Doing this will give you full access to the forums, where you will be able to receive personalized advice concerning your pool. We hope to see you soon!

Patio Crack

I know this isn't necessarily pool related but very similar. I have a patio that has a crack in it. I just wanted to see if anyone wanted to give me their opinion on how it should be fixed. My house is only just over 2 years old. This crack appeared only a month after they poured the patio or less. The builder said they would epoxy coat the patio to prevent it from getting worse at the time. Well they haven't done anything and I put in a complaint to get it fixed. Their concrete guy came out and said they were going to grind down the top surface and put a new layer on top.

Well now I'm starting to think this crack is worse than just an imperfection. It seems to keep getting wider slowly and at the end of the patio is now spidering into three cracks. So far the builder has put this off for way too long and I'm thinking about elevating the severity.

So anyone think they would have to replace the entire patio or would grinding down the top and pouring a new top layer fix this?

Cracks that follow the line of the house are often caused by uneven settling of the dirt under the deck. Often the dirt right next to the house has been compacted very well and the new dirt further away has not been compacted as well. The dirt further from the house settles over time and the deck cracks. Typically such cracks are a cosmetic problem more than anything. They can continue to shift and grow as long as the dirt continues to settle but rarely become serious.

While it could be settlement, I believe it is more likely due to concrete shrinkage. Concrete can shrink about 3%. The crack looks like a shrinkage crack to me. Concrete shrinks -- period. There are things that can be done to minimize it, though. A few things that can happen:

- If the mix has a high water/cement ratio (too wet) the conrete will shrink a lot more. A good mix design (not the cheapest one) will have a w/c ratio of maybe .55 at the highest. As a secondary bennefit, this will result in a higher strength concrete as well. This concrete can be harder to place and finish, so many contractors opt for the lower strength, higher shrinkage concrete. This can be OK if other things are done....

- As all concrete shrinks to some degree, even the best concrete will decide to crack in the most visable place. The use of control joints does not prevent the cracks, but encourages them to be in a spot pre-arranged by you. These joints van be trouwled in or saw-cut. The crack will form at the weakest place -- in the joint you created. Use as many of these as you can tolerate.

- reinforcing. No reinforcing steel = cracks. Again, the concrete may crack, but the reinforcing will help these cracks stay small -- or eliminate them if the slab is small enough. If small enough, the reinforcing will help the concrete pull in from all edges instead of crack in the middle. Make sure you have steel in your slab! There are a few types -- welded wire mesh or deformed steel bar (re-bar). The mesh works, but not as well as the re-bar. In a 4" slab, #3 bars at 15" each way is the smallest recommended by code for crack control (0.0018 times the area). The mesh has a hard time achieving this - -especially the smaller mesh most contractors use. Note that the thicker the concrete, the higher the shrinkage stresses and the more reinforcing that is needed.

- placement of reinforcing. The placement of the reinforcing is very important. It's common with mesh to not chair it up on blocks but to try (note 'try') to pull it up to the middle of the concrete slab while the concrete is being poured. I've seen plenty of slabs with the reinforcement in the dirt where it's useless.

- restraint. If the slab can't move when it shrinks, it'll crack in some odd places. If the slab is poured in an 'L' shape around a corner of the house, you can imagine the slab trying to shrink -- and even with the right steel, something's got to break -- and it won't be your house. If the slab is in an odd shape, place it in two pours.

I am specifying a 5" slab with #3 at 12" each way and a w/c of 0.50 and plenty of joints. This is way overkill, but I HATE cracks!

Shrinkage cracks typically occur in the first month (usually sooner) after placing the concrete.

As for repair -- a coat of epoxy over the top won't cover the cracks. The cracks should be epoxy injected (not a DIY projcet) which makes the crack go away, but not pretty (you've seen the cracks filled in the floor of your local Home Depot) and then it can be topped. There are products that can top the slab.

Some just tile over the top -- but the crack must be filled first (see above).

If the crack is not sue to shrinkage, but doe to settlement, it'll re-crack. Monitor it for a few months and see if it getts larger. If it's shrinkage, it should do it's thing and stop. If the crack keeps getting larger, it's somehting else.

Thanks for the input. I'm getting most concerned about the cracks showing up at the end where it splits to three cracks. Thats new and it seems the crack on that end of the patio keeps getting bigger. It started as a hairline crack and has gotten just a tad bigger till you can almost get a dime edge in the crack.

how long has it been since it was poured? I've seen concrete get 3/8" cracks if not the right mix design, not enough joints and a long enough slab. If it's shrinkage it should not get much bigger after a month or two. If it is, it's probably settlement.

This patio was poured 2 1/2 years ago. So it's been a lot longer than a couple months. I think I'm going to bite the bullet and have the slap inspected just to play it on the safe side.

Inspected for what? Even if it's settlement -- what will you do with the information? If this crack bothers you, put the $$ from having it inspected toward having it replaced. You can live with it or you can't.

If the crack showed up 2.5 yrs after it was poured -- not shrinkage.

(you shouls see the cracks that 'showed up' in our driveway from the dirt and concrete trucks as they are building out pool.... shifter it around and demolished the end 18" of it. That's why they get the waiver signed at the beginning.

Well the reason I want to have it inspected is because the builder is still liable to fix the patio. Here in AZ you have by law six years after construction of a home to get things fixed that are building defects. Right now the builder has been very unresponsive in fixing it and a few other "issues" so I might have to complain to the registrar of contractors. My house has only been complete for just over two years.